<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .container {
            width:500px;
            background-color: orange;
            overflow: hidden;
            clear:both;
        }
        .box1 {
             width: 100px;
             height: 100px;
             background-color: blue;
            margin: 10px;
             float: left;
         }
        .box2 {
            width: 100px;
            height: 100px;
            background-color: green;
            clear: both;
        }

    </style>
</head>
<body>
    <div class="container">
        <div class="box1"></div>
        <div class="box2"></div>
    </div>
</body>
</html>